GM-GMC: cabin air filter, cabin air filters, cabin air filter

Question
1998 silverado c1500 series v8 5.7
I want to replace the cabin filter but I'm having a problem to find it.
also the passenger seat belt( lap or waist part) always lock up when its fasten.can you help me please! thanks

Answer
I believe they started putting cabin air filters into the silverado in 1999, behind the glove box usually.  As for the seat belt, there is a mechanism that governs when the belt locks.  It is not uncommon for them to malfunction.  Really the only thing that is recommended is to look down inside and make sure there isn't anything jamming it.  Other than that replacement is recommended.
hope this helps